Insights into the opacification mechanism of lead-barium glass in China

Ancient Chinese craftsmen developed a distinctive type of glass with high PbO and BaO — known as lead-barium glass — primarily for imitating jade. Previous studies have established a correlation between the opacity of lead-barium glass and the presence of BaO, but this finding fails to account for the variations in transparency, as they could be divided clearly into translucent and opaque. This study examines typical opaque and translucent samples using SEM-EDS and Raman spectroscopy. The results prove distinct differences between opaque and translucent lead-barium glass, particularly in the microstructure and raw materials. Opaque glass possesses a more complex microstructure, containing numerous bubbles, unfused particles, and crystalline inclusions. It was produced using barite (BaSO₄) and galena (PbS), while translucent glass likely employed refined lead compounds and witherite (BaCO₃). These distinctions help clarify the opacification mechanism, enhancing our understanding of jade imitation technology and its cultural relevance in ancient China.